A system of the above-described type is disclosed in DE-AS No. 24 11 871. This system allows transmission of analog or digital signals over regenerating circuits which also isolate the floating transmission line from ground connections at the transmitting and receiving sides. A high transmission speed and a very exact signal regeneration without the application of special voltages can be accomplished.
In the regeneration of signals, and in particular in the regeneration of signals having relatively small amplitudes, it is important that the regenerated signal and the input data signal have a linear relationship to each other. Thus the rectification which takes place on the secondary side should have as few losses as possible. On the other hand, in the absence of signals to be regenerated, the output of the regenerating circuit should have as high an impedance as possible. This is particularly important in data transmission systems in which the transmission lines may be connected to more than one transmitting and/or receiving unit. A unit which is not in operation should present a high impedance to the transmission line to avoid changes in the characteristic impedance of the line and, further, should present a high impedance to any unit that may be in operation, so that such a unit is not overloaded.